Thyroidectomy has evolved over the years with an emphasis on capsular dissection and the identification and preservation of vital structures [6]. The major complications of thyroidectomy include injury to the recurrent laryngeal nerve and accidental removal of parathyroid glands [7–9].
In our study with a sample size of 80, we found the rate of temporary hypocalcaemia was 7.6% (out of 39 total thyroidectomies), temporary recurrent laryngeal nerve injury was 0.8% and permanent recurrent laryngeal nerve injury was 2.5%t (3 out of 119 nerves at risk). Identification of these structures is paramount to prevent inadvertent injury.
Injury to the recurrent laryngeal nerve following thyroidectomy significantly impacts the quality of life of the patient [10, 11]. The recurrent laryngeal nerve has several variations and is not always easy to identify [12]. Although neuromonitoring of RLN has been used to prevent injury to the nerve, the data does not conclusively prove its effectiveness [2]. Hypocalcaemia is defined as serum calcium of less than 8 milligrams per decilitre, 24 hours after thyroid surgery [8]. Prevention of hypoparathyroidism following thyroidectomy requires the preservation of parathyroids along with their blood supply. This can be achieved by identifying the parathyroids by their anatomical location and appearance and by meticulous capsular dissection during thyroidectomy [9]. Recent studies have explored NIRAF as a tool to preserve parathyroids, but the effectiveness of this in preventing long-term hypocalcaemia has not been conclusively proven [3]. An ideal method to completely preserve a functioning nerve and parathyroid remains elusive and good knowledge of anatomy and physically identifying the above structures will remain a standard operative technique in thyroidectomies. The use of loupes will be a very useful, cost-effective and pragmatic tool for safe and effective thyroidectomy even in small volume centres or resource-constrained environments.
Literature states the rate of injury to a recurrent laryngeal nerve is between 5 to 11% and the rate of hypocalcaemia between 5 to 30% following thyroidectomy [8–11]. Few papers have compared the outcome of thyroidectomy with and without loupes. A comparative study by K Das [13] showed a hypocalcaemia rate of 37.5% following thyroidectomy without loupes when compared to 7.6% with loupes. The recurrent laryngeal nerve injury was 29.1% and 7.6% in the groups without and with loupes respectively. A similar study by Nagaty et.al [14] had recurrent laryngeal nerve palsy of 2.5% and hypocalcaemia of 10% when thyroidectomy was performed using loupes. A paper by D’Orazi et. al [15] studied 782 thyroidectomies with loupes and reported recurrent laryngeal nerve injury at 0.77% and transient hypocalcaemia at around 11%. (Table 1) A systematic review by Sapalidis et.al [5] compared the results of magnification techniques and direct vision thyroidectomy and concluded there was no effect on magnification on transient nerve palsy and transient hypocalcaemia, but needed more data to study the effect on permanent nerve palsy and hypocalcaemia.
Surgical loupes have been used widely in dentistry and reconstructive and microvascular surgeries. Loupes are magnifying devices [16]. Surgical loupes are largely classified as Galilean loupes and prismatic loupes (Fig. 3). Galilean loupes have a system of lenses separated by air whereas prismatic loupes use the Schmidt prism [17]. Prismatic loupes give higher magnification, a greater field of view and longer working distance but come with the disadvantage of higher cost. Although a microscope has been used to identify RLN in thyroid surgery (19), it would be easy and prudent to use a loupe for its ease of use and wide field view. The senior authors have used customised Galilean loupes of 2.5 and 3.5 X, and they find that it gives the right combination of ergonomics, flexibility, wide field view, resolution, magnification, focal length and protection from spillage. The disadvantages are fogging, neck strain, and fatigue when not customised. Loupes are very useful in other head and neck surgeries (like Parotid surgeries) and can be used as an alternative to nerve monitoring [18], or also in conjunction with better outcomes in thyroidectomies.
The main disadvantage of the study is not having a control group; however, it would be difficult to do such studies without a very big sample size. Further, it would be a challenge for the surgeon who is already accustomed to loupes to go back to non-magnification surgery just for trial or research purposes.
Table 1
Comparison of Studies showing the impact of magnification on results of thyroidectomy
| Study | Sample size | Magnification | RLN palsy | Hypocalcemia |
| D Orazi et.al 2016 [15] | 782 | 4.5x Loupes | 0.77% | 11% |
| Das K et.al 2021[13] | 50 + 50 | Loupes | 2% | 7.6% |
| Nagaty et.al 2023[14] | 40 + 40 | 2.5x loupes | 2.5% | 10% |
| Satish Jain et.al 2020[19] | 878 | Microscope | 1.52% | 8.12% |
| Saber et.al 2011[20] | 121 | Loupes | 0.8% | 1.65 |
| Testini et.al 2004 [21] | 47 + 50 | 2.5x loupes | 0 | 4.2% |
| Seven et.al [22] | 58 + 40 | Microscope | 1.7% | 1.7% |
| Present study | 80 | 2.5 x Loupes | 2.5% | 7.6%(transient) |